Electric fuse.



l. MARCUS.

ELECTRIC FUSE.

APPucATlon mso Noyau. 191s.

1 ,265,223. Pawntd May-7, 1918.

avana/Lto:

I. MARCUS 0 QA l l `J l l y @Hoz/Mago ISRAEL LIARCJ'S,4 01"' WINTHROP, MASSACHUSETTS.

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Patented May '7, 1918.

Application met! November 27, 1916. Serial No. 133,704.

To all whom tmc concern.-

l Be it known that I, ISRAEL Minions, a citizen of the United States, `residin at Winthrop, in the county of Suffolk and State of Massachusetts, have invented cer- -tain new and useful Improvements in Electric Fuses' and I do declare the following to be a fu l, clear, and exactdescription of the invention, such as -will enable others skilled in the art to which it appertains to make and use the same.

This invention relates to improvements in electric fuses or cut-outs whereb anelectric circuit is broken whenever t e amount of electricity passing through the. fuse is greater than can be circuit of which'said fuseis a part.

The primary object of the .present invention is to provide a fuse, the fuse wire of which is so weakened at 'one point that the severance of the wire is bound to occur 'at this point when there is an overload' on the circuit.

A secondary object is to provide a simply constructed fuse having a sight opening in one wall of the casing thereof through which it can be determined whether or not ,the fuse wire therein is broken.

With these and other objects in view the invention resides in the novel features of construction, combination and arrangement of parts which will be hereinafter more par ticularly described and claimed and shown in the drawings wherein:

Figure 1 iepresents a side elevation of a fuse constructed in accordance with my invention;

Fig. 2 is a horizontal longitudinal section on the line 2 2 of Fig. 3

Fig. 3 is a sectional view on a plane at right angles to Fig. 2 on the line 3 3 of Fig. 1; and,

Figs. 4 and 5 are transverse sections taken respectively upon the lines 4 4 and 5 5 of Fig. 3.

Referrinur more particularly -to the several fi ures o the accompanying drawing w erein the details of the invention are clearly shown, the numeral 1 desi etes a preferably cylindrical casing formetgf fiber or any other cheap material which is not readily combustible and 2 the caps of copper or brass which close the open ends of the casing. These caps 2 which form the contact portions of the fuse are of any preferred formation, such as fely carried by the' theI construction illustrated and are adapted to disposed between the spring contact fingers disposed upon a switch board or the like.

The interior construction of this improved fuse is shown clearly in Figs. 2 and 3 where` in it will be seen that a fuse 3 of .relatively large diameter connects the bases 4 of the cap members 2, the ends of said wire 3 preferably being inserted through circular openings 5 in the center of the portions 4 of Said caps and soldered. This f e wire 3 Ais formed of lead or other soft etal having a low Anielting point. When the fuse is iii operation although the major portion of the current passes through the large fuse wire 3, a portion of said current will pass through a supplemental fuse wire 6 of erman silver wirc,'said -wire being of very small diameter so4 as to give it a rather high resistance.

he purpose of this supplemental fuse wire 6 will hereinafter more particularly pointed out.

I have discovered that cning the fuse wire at a certain oint it will alwafys break at this point w en the current o electricity rises above the safety point. Iirthe present device I carry out this idea by flattening or otherwise materially reducing the cross sectional area of the fuse wire 3 at a point substantially midway its ends as shown at 7. Thus when the current passing through the,4 wire 3 becomes too great, the excess heat will melt the wire at the point 7. Opposite this poiiit 7 a sight openingc is formed in the wall of the cylinder or tube 1 of the casing so that it can always be seen whether or not the fuse will conduct the electricity.

Since it is necessary said in e o ening aterallytowardt e side 8, said wire is bent the opening. This e tube containing e inner wall o fthe',

by materially weak-l formation is seen from Fig. 3 wherein it will be noted that said wire is substantially bowed throughout its length.

It is essential that the powdered asbestos 9 he prevented from sifting between the fuse wire 3 and the sight opening 8, therefore an additional sheet or plate ot' mica '11 is disposed nround the inside of the fuse wire 3 and has its longitudinal edges cemented to the first mentioned plete 10 or to the adjacent portion of the wall of the cylinder l.

From the foregoing description it will be seen that an extremely simple fuse has been produced whereby one um y readily and positively determine whether or not it is capable of conducting electricity. ln other words by simply glancing through the sight opening 3 it can bc noted u'hetlieror not the fuse wire is broken at the point 7. rl`he sul'iplenit-,ntnl fuse wire G whosc ends are also connecte the metallic caps 2 prevents the main fuse Wire 'from sparking or sputtering when itis burning through. As soon as the main wire 3 is broken at the point T the full charge o ihc current inust pass through the supplemental wire (i, it however immediately Vmelts due to the great heat generated wheirthe electrical circuit is broken. Various changes inny be iii-.ide in the positions of the sight openings in the different types of fuses as well es the means for reducing the cross sectional area. o the fuse wire 3 at a particular oint, without departing from the principles of the invention as outlined in the claims I claim: A device of the class described comprising :i cylindrical casing having slot disposed midway its endsz caps fitted over the ends of said Casin having centrally elined apertures, :i pair o non-combusti le transparent plates positioned over said slot, one of said plates being transversely curved to conform to the curvature of the inner well of said casing an the other having its central fportion bulged away from said rst mentioned plate, a fuse wire having n reduced middle portion disposed between said plates in the space formed by said bulge, the endsl ot' said fuse wire being bent laterally and disposed in thel apertures in said caps, a second fuse wire disposed within the 'apertures in the caps an positioned at substuntiilll y right :ingles to Said first mentioned wire whereby to prevent sparking when said first mentioned fuse wire is blown and loose non-combustible material disposed in said easing to fill the same and space seid wires. In testimonvwhereo I have hereunto set in hand in the presence of two subscribing witnesses.

ISRAEL MARCUS.

Witnesses:

MARGARET L. Flaminia, J AMES A. WATERS.

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